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End of Chapter 6
The forces of chaos truly live up to their name. Needless to say, studying chaos is chaotic itself. Transition sates and intermediates Reactions often involve multiple steps. As you can see in the diagram to the right, the local minima in the reaction represent the intermediates, '''and the local maxima represent the '''transition states. A transition state is a state through which the reaction passes. They occur while bonds are breaking and reforming during a reaction. They are unstable, and are unable to be isolated. They can potentially live for less than 10^-15 seconds. The intermediate is a product of a reaction that is not the final step of the reaction. They can live up to 10^-6 secondscitation needed. Hammond Postulate?Nah Gibbs free energy tl:dr ∆G-The energy difference between reactants and products ∆Gキ :energy difference between reactant and transition state structure of each step How fast something can occur is 'buried' in the y-axis on the energy graph. See, it doesn't show time, but instead reaction progress. ∆Gキ can tell you how fast something can occur, but it depends on how much heat you put in a systemwtf? Rate determining step: the step with the largest ∆Gキ determines the ultimate rate of the reaction. Also catalysts are not used in the reaction Nucleophiles and Electrophiles Every reaction is between a nucleophile and an electrophile. Every. Reaction.(or atleast every relevant one) Lewis bases? Lewis acids? Fuck that shit, we got Nucleophiles and Electrophiles now. Lewis was a scrub who couldn't keep up. What kind of atoms are nucleophiles? Every Lewis base+ atoms with pi bonds. All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because they donate electrons, they are by definition Lewis bases Nucleophiles include: Anions, any atom in a molecule with a lone pair besides bonded halogens, and atoms with pi bonds. On the other hand, all Lewis acids are electrophiles This means that cations, group 3 atoms, group 6 atoms that are bonded to hydrogen, and group 7 atoms bonded to hydrogen are all electrophiles Arrows Recall that a mechanism shows how a reaction takes place using curved arrows to illustrate the flow of elections. The tail of every curved arrow shows where the electrons are coming from, and the head of every curved arrow shows where the electrons are going. In order to master ionic mechanism, it will be helpful to become familiar with characteristic patterns for arrow pushing. Nucleophilic attack The first pattern is nucleophilic attack, characterized by a nucleophile attacking an electrophile. Loss of Leaving Group The second pattern for arrow pushing is characterized by the loss of a leaving group. Proton Transfers The third pattern for arrow pushing is proton transfer, which you should already know but don't since it was a while ago when it was relevant. Rearrangements The fourth and final pattern is characterized by rearrangement. There are several kinds, but we will focus on carbocation rearrangements.